Glimmers of hope in large carnivore recoveries

In the face of an accelerating extinction crisis, scientists must draw insights from successful conservation interventions to uncover promising strategies for reversing broader declines. Here, we synthesize cases of recovery from a list of 362 species of large carnivores, ecologically important species that function as terminal consumers in many ecological contexts. Large carnivores represent critical conservation targets that have experienced historical declines as a result of direct exploitation and habitat loss. We examine taxonomic and geographic variation in current extinction risk and recovery indices, identify conservation actions associated with positive outcomes, and reveal anthropogenic threats linked to ongoing declines. We find that fewer than 10% of global large carnivore populations are increasing, and only 12 species (3.3%) have experienced genuine improvement in extinction risk, mostly limited to recoveries among marine mammals. Recovery is associated with species legislation enacted at national and international levels, and with management of direct exploitation. Conversely, ongoing declines are robustly linked to threats that include habitat modification and human conflict. Applying lessons from cases of large carnivore recovery will be crucial for restoring intact ecosystems and maintaining the services they provide to humans.

Patterns of extinction risk. We identified 362 vertebrate species distributed across all major ecosystem types ( Fig. S1) that met our criteria and to which the IUCN has assigned a known extinction risk category. Overall, 38% [35%-43%] of large carnivore species are considered threatened (encompassing 'Vulnerable' , 'Endangered' , or 'Critically Endangered' species; lower and upper bounds reflect the uncertainty introduced by Data Deficient species). This represents a substantially higher proportion of threatened species compared to Red List averages of 27% for all species and 18% for all vertebrates. Among these species, extinction risk is unevenly distributed across geographic regions. Large carnivore species in the Nearctic and Australasia regions show a lower proportion of threatened species (13%, and 27% threatened, respectively); compared with the Afrotropic (39%) and Indo-Malay regions (41%). We note that developed regions with lower proportions of threatened species have previously lost sensitive megafauna to Pleistocene extinctions 28 , export a sizeable share of their environmental impacts 29 , and show lower rates of increase of human population compared with developing regions 30 .
Extinction risk also varied widely among vertebrate groups (Fig. 1). Marine mammals show the lowest proportion of threatened species (27% threatened [20%-44%]) offering a stark contrast with the high extinction risk among sharks and rays (61% threatened [55%-65%]). Indeed, while more than half of all large carnivore species are categorized Least Concern, only 17% of shark species occupy this lowest extinction risk category ( Fig. 2; Table S1). The wide disparity in status for these two groups of marine megafauna corroborates evidence that while the cessation of industrial exploitation of marine mammals has initiated successful recoveries within this group 31 , many shark species remain intensely and unsustainably exploited 17,32 . As these groups of marine megafauna show little functional redundancy 33 , ongoing declines among sharks are likely to have deleterious ecological effects, including mesopredator release and altered carbon dynamics 34 . Among the remaining taxa, fully half of terrestrial mammals are listed as threatened, nearly double the rate of all IUCN mammal species. Further, roughly one-third of reptiles, birds, and bony fishes are threatened, compared with taxon-wide rates of 34%, 14%, 6% respectively. Large carnivore recoveries. On its own, current extinction risk provides only a snapshot of conservation status. We therefore assessed two temporal metrics indicative of recovery: (1) an IUCN-listed 'increasing' population trend and (2) a cumulative improvement in status since the species' first comprehensive assessment under the modern IUCN system (ranging from 1996 to 2001, depending on taxon). Importantly, we considered only genuine improvements that came as a result of conservation efforts, excluding changes that resulted from improved assessment data or from IUCN criteria changes 35 . Approximately 10% of large carnivores (39 species) displayed one or both indicators of recovery, and recoveries were highly concentrated within particular vertebrate groups, including birds and marine mammals. Marine mammals showed higher than expected number of species with both increasing trend (p > 0.001; Bonferroni-corrected, post-hoc binomial test; Table S2) and genuine status improvement (p > 0.001), highlighted by dramatic improvements in status of humpback whales (Megaptera novaeangliae) and Steller sea lions (Eumetopias jubatus) (Fig. 3). Few genuine status improvements fell outside of the marine mammals and no other vertebrate group showed higher than expected number of species with either recovery metric (Table S2). Baleen whales alone represented nearly 18% of all recoveries and, omitting marine mammals, the proportion of recoveries among remaining taxa dropped to 7.3% (21 of 294 species). While birds showed a number of species with increasing trend (n = 14; Table S4), many species in this group remain in peril. We identified only a single terrestrial mammal, the Iberian lynx (Lynx pardinus), that met either recovery criterion.
Recovery was similarly uneven with respect to geography (Table S3; Figs. S2-S3). Compared to expected proportions based on the global prevalence of large carnivore predator recovery, the Nearctic realm had a significantly greater proportion of species with an increasing population trend (47% increasing, p < 0.001, Bonferroni-corrected, post-hoc binomial test) and with improved IUCN status (7% improved, p < 0.001). In contrast, the Afrotropic and Indo-Malay realms showed significantly higher than expected proportions of species with a decreasing trend (62%, p = 0.008 and 72%, p < 0.001, respectively) and status declines (18% and 7%, p < 0.001 for both). Among marine realms, several temperate and polar regions showed greater than expected proportions of species with improvements in status (Northern Temperate and Arctic Oceans, 7%; Northwest Pacific, 5%; Southeast Pacific 7%, and Southern Ocean, 10%; p < 0.001 for each), driven largely by marine mammal recoveries.
Conservation strategies associated with recovery. This variation in recovery outcomes allowed us to explore the categories of conservation interventions (Table S5) positively associated with large carnivore recovery using binomial logistic regression. Recoveries were associated with species legislation enacted at national and international levels, and with harvest plans that reduce uncontrolled exploitation (Fig. 4). Specifically, the odds of an improvement in extinction risk increased 6.8-fold [CI 1.9-122.9] for species subject to international legislation and threefold ] for species with a harvest management plan in place (using IUCN-defined categories; Table S5). Similarly, the odds of an increasing population trend more than doubled for species subject to international legislation and those with conservation sites identified (Fig. 4b). Under IUCN guidance, conservation sites identified may or may be receiving protection (see Table S5 for details) and this action should not be confused with area protection, which was not associated with either indicator of recovery. We note two important caveats. First, among IUCN Red List assessments, 'Conservation Actions In-place' fields are inconsistently completed (IUCN Red List, pers comms.). Second, several species with near total harvest bans (e.g., marine mammals) are listed as having harvest management plan in-place, likely driving the association with recovery. Indeed, with marine mammals omitted from the analysis, harvest management plans did not significantly increase the odds of a status improvement (CI − 2.1-+ 3.9). In response to these limitations www.nature.com/scientificreports/ of IUCN-defined categories, the authors compiled a separate list of conservation interventions applied to large carnivores (see "Methods" and Table S5) and further tested associations with recovery metrics. From models using author-defined conservation categories, species with national legislation were 13 times more likely to have a positive than a negative recovery outcome [CI 1.9-122.9] (Fig. 4c). Our analysis underlines evidence that legal protections at the national level can be instrumental in facilitating wildlife recoveries. Notably, recoveries were disproportionately found in developed regions where the application of strong legislation and management of exploitation is made possible by effective governance and enforcement. For example, the eastern population of Steller sea lions (Eumetopias jubatus) has increased 2% per year between 2000 and 2015 as a result of strong national legislation, which has provided the leverage to reduce direct mortality and to identify and protect critical rookery habitat 36 . This example corroborates broader evidence that strongly enforced limits on direct mortality coupled with the identification of critical habitat enhances recovery 37 and offers a timely reminder of the value of national legislation as the United States emerges from a period of pronounced deregulation 38 .
Legal protections have also been crucial for the recovery of high-trophic level birds, from the regulation of the insecticide DDT (banned in 1972 in the United States and Canada; most western European countries in the 1980s) to more recent agreements 39,40 . Yet despite regulations, large avian carnivores remain vulnerable, as demonstrated by the catastrophic declines of South Asian vultures, driven largely by the use of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac to treat livestock in this region 41 . Moreover, the recent licensing of diclofenac for veterinary use in several southern European countries could lead to thousands of vulture deaths a year 42 , potentially undermining a regional bright spot in our analysis-the Iberian Peninsula. More encouragingly, conservation research on South Asian vultures has progressed from identifying primary threats to designing, implementing, and testing effective interventions (including safe alternatives to diclofenac); ongoing monitoring suggests shallower declines and even the incipient recovery of some vulture populations 43 . These contrasting case studies demonstrate the importance of enforceable regulation at the national level, and of providing alternatives to prohibited activities.
In contrast, we found no support for a positive effect of area protection (i.e., parks and refuges), a result that should be interpreted cautiously and with context. Considerable evidence suggests that protected areas can be an effective tool for conserving megafauna on land 44 and in the ocean 45 . Yet, many parks are poorly enforced ('paper parks') with exhibit low levels of compliance with park restrictions 46,47 , reducing their effectiveness in achieving conservation aims 48 . The lack of detectable effects of area protection on recoveries may also stem from   Table S1. www.nature.com/scientificreports/ inadequate size and lack of connectivity with habitats outside of parks 49 as even large protected areas offer only partial refuge for highly mobile predators 50 .Thus, our results reinforce the message that area protection should be accompanied by addressing conditions that enable their success-within and beyond park boundaries 51 .
Reversing ongoing declines. Complementing our analysis of conservation actions associated with recovery, the negative outcomes in the data also enabled us to identify anthropogenic threats associated with ongoing declines. We tested whether 23 categories of threat (Tables S6 and S7) were associated with any of the three negative outcomes: high extinction risk, declines in status through time, and decreasing population trend. Among these, five threats were significantly linked with negative outcomes (Fig. 5) and three of these (conflict, ecosystem modification, and hydrological modification) were associated with multiple metrics of decline. Specifically, species that whose range included conflict zones ("conflict" here denotes war or instability, rather than human-wildlife conflict) had a 37-fold increase in the odds of elevated extinction risk [CI 4.6-890] and a 7.4fold increase in the odds of a decreasing population trend [CI 1. . We note that the effects of conflict may disproportionately affect terrestrial megafauna; consequences for the conservation of large marine predators remains relatively understudied and merits future research. Recent work has documented the corrosive effect of armed conflict on the stable governance and civil institutions critical for conservation, and our findings indicate that the links between warfare and wildlife declines observed in African parks 52 may hold for large carnivores globally. Such instability may emerge as an even greater threat to large carnivore recovery in the near future, given growing human populations, the global rise in income inequality, and the potential for climate change to exacerbate resource conflicts. Therefore, scalable and rapid-response interventions that simultaneously alleviate the effects of conflict on humans and wildlife will become increasingly critical. Encouragingly, there is some evidence that recovery remains possible even in regions of frequent conflict given timely, post-conflict interventions-particularly those that link wildlife rehabilitation to poverty alleviation 53 . More broadly, effective predator conservation in the developing world may require an alternative model to that of developed nations: given the competing pressures of poverty and other social concerns, collaborative approaches emphasizing local engagement, psychological ownership, and capacity building may be more effective than top-down, legislative approaches 54    www.nature.com/scientificreports/ depredated livestock, and by employing respected community members to reinforce predator-tolerance behaviors and encourage a sense of community ownership for predators 55 . While education and awareness approaches were not associated with recoveries in our global analysis, examples such as this highlight the efficacy of well-designed social interventions in rural and developing regions. In addition, ecosystem modification was linked with elevated extinction risk [8.9-fold increase; CI 1.7-84] and status decline [5.6-fold increase; CI 1.9-29] and hydrological changes (e.g., dam construction) were associated with declining status [4.0-fold increase; CI 1. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and with decreasing trend [4.5-fold increase; CI 1. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. These threats are particularly acute for fishes in Asia and Africa where construction of dams 56 and conversion of mangrove habitat 57 is accelerating. Accordingly, bony fishes in the combined Indo-Malay and Afrotropic regions showed the highest proportion of threatened species among all taxon/region combinations in our analysis (44%). Among other taxon/region combinations, the Indo-Malay and Afrotropic birds were disproportionately represented among species experiencing ongoing declines, in particular African eagles and vultures (Fig. 3, Table S4). Declines among these scavengers has been attributed to inadvertent poisoning (when vultures consume poisoned baits targeting predators), trade in body parts for medicinal use, and direct persecution by poachers (due to their role in signaling authorities of illicit activity) 59,60 . Globally, dietary toxins represents the most prevalent threat facing vultures 61 , but it is notable that scavengers-uniquely among the species in our analysis-rely on provisioning of carrion by predators and may therefore be subject to the compounding effect of declines in other large carnivores from our study ("chain of extinction"). While more difficult to quantify, the impact of wildlife declines across Africa has likely affected vulture populations, in turn 60 , highlighting the critical importance of large carnivore recovery. Indeed, with scavenging species omitted, the association between ecosystem www.nature.com/scientificreports/ modification and negative outcomes was no longer significant (Table S8), perhaps reflecting indirect effects on vultures mediated through habitat-and prey-loss for the predators on which they rely. Even more directly, the association between status declines and transportation disappeared with vultures omitted, underling the vulnerability of scavenging species to road-strikes.

Discussion
Large carnivore recovery represents a unique opportunity for reversing broader degradation of ecosystems. As some of nature's most charismatic species, many serve as national symbols and flagship species whose conservation can indirectly benefit other species and increase support for about conservation initiatives 62 . Our global synthesis documents rare cases of recovery among large carnivore species and underlines the importance of species legislation and restricting or eliminating exploitation for recovery success. While the utility of these conservation actions has been previously demonstrated in finer-scale analyses, our work emphasizes the generality of these findings for large carnivores globally and provides an important cross-taxon comparison of their implementation. We further uncovered robust links between ongoing declines and specific anthropogenic threats, including human conflict, habitat modification, and hydrological changes. A core message that emerges is that well-enforced legislation and management of exploitation can underpin large carnivore recovery by addressing uncontrolled mortality and habitat degradation that can occur in the absence of effective governance. Our findings illuminate large-scale patterns that can serve as hypotheses for exploring the variation in recovery within species and among populations and are best viewed as a complement to important and ongoing species-specific and regional analyses 63 . A detailed policy review of specific legal provisions, the extent of enforcement, and the resulting magnitude of recovery is beyond the scope of our analysis but represents an important future direction. Nevertheless, it is instructive that these results have emerged from a global, cross-taxon analysis despite the inherent variability in such an effort. Examining rare glimmers of hope among large carnivore recoveries can highlight strategies for reversing population declines that remain more common within this group. Recoveries that buck taxonomic trends are instructive as exceptions that illuminate the rule: although recovery for sharks as a whole was not encouraging, successful rebuilding of elasmobranch populations has occurred in the small number of cases where exploitation limits are grounded in science and strictly enforced 17,64 . Indeed, one of the bright spots from our analysis, the smooth skate (Dipturus innominatus) owes its recovery to inclusion in New Zealand's quota management system, which has resulted in newly sustainable harvest levels 65 . We caution against inferring from this example that sustainable exploitation is achievable for all large carnivore species, however. Factors including K-selected life-history traits and social group dynamics can mean that even modest levels of exploitation can result in large carnivore population declines 66 and exploitation policies must align with ecological realities.
Recoveries in human-occupied landscapes are particularly encouraging and instructive. For example, the Spanish imperial eagle (Aquila adalberti) declined to near extinction on the intensively altered Iberian Peninsula as a result of ecosystem modification and resultant loss of prey, as well as inadvertent poisoning and electrocution 67 . Strong species recovery since the 2000s, largely outside of protected areas, has been attributed to the replacement of electrical infrastructure and to programs supporting eagle-friendly land management and prey protection on private lands 68 . This example demonstrates that large carnivore declines can be reversed even in regions with limited public lands by addressing critical threats in partnership with private landowners.
Many large carnivore species have vast ranges encompassing several countries, complicating both the implementation of conservation interventions and the assessment of their effectiveness. For example, globally, tigers (Panthera tigris) have been extirpated from 94% of their historic range 69 and remain Endangered with a decreasing population trend. Yet regional, national, and landscape-scale interventions are showing promise for tiger recovery: an ambitious program involving all 13 tiger-occupied countries are underway with the goal of doubling the global population through preserving habitat, eradicating poaching and illegal trading, and engaging with local communities 70 . Indeed, Nepal has nearly doubled its Bengal tiger population since 2009 through locally tailored efforts aimed at reducing human-wildlife conflict and supporting the well-being of communities that share landscapes with tigers 71 .
For the many species whose home range spans multiple jurisdictions, regulating exploitation and protecting sensitive habitats requires consistency and cooperation across state/territorial and international borders 39,40 . Accordingly, international protections also showed a positive association with successful large carnivore recovery, exemplified by the moratorium on commercial whaling 31 . The future success of international agreements aimed at large carnivore recovery will rely on responsive trans-jurisdictional governance, especially as species ranges' shift with climate change 72 . At present, negotiations are underway for a UN treaty on conservation of the 'highseas' (marine regions that fall outside any national jurisdictions), an agreement that is particularly critical for reversing ongoing declines in pelagic sharks and migratory tunas (Fig. 2).
Our analysis also revealed important data gaps. Despite the ecological and symbolic importance of large carnivore, only 65% of assessed species were assigned to definitive status and trend categories: 33 species were considered Data Deficient, including iconic predators such as the Killer whale (Orcinus orca) and an additional 103 assessed species had an unknown population trend. Moreover, many assessments are quite dated, limiting their utility for assessing real-time extinction risk and instantaneous population trends (while remaining useful for an analysis of historical recoveries and declines, as presented here). At the time of writing, 25% of assessments had not been updated for over a decade, with reptile assessments being particularly outdated (median age 9.6 years; Fig. S4). These gaps highlight the ongoing shortfall in investment in research and monitoring of wildlife populations-even among charismatic species that are widely perceived by the public to be well-studied and adequately protected 73  www.nature.com/scientificreports/ A sustainable future: large carnivore recoveries in human-nature systems. Looking ahead, Anthropocene recovery strategies for large carnivores must be effective not only in largely unaltered landscapes, but also where ecosystems simultaneously sustain human livelihoods. It is in these shared landscapes and seascapes that the potential downsides of large carnivore recovery for humans are most acute 74 . Positive steps forward include maximizing social tolerance for and coexistence with predators 75,76 , as well as developing low-cost methods of reducing human risk 77 . Conversely, segregating human and carnivore activities 78 and erecting physical barriers 79 represent promising alternatives to culling, particularly when both human and predator safety is integrated into the design 80 . Direct harvesting for human consumption or medicinal uses has historically been the greatest individual threat to megafauna across major classes of large terrestrial, freshwater, and marine vertebrates, and this overexploitation remains a major impediment to megafauna recoveries 16 . Moreover, new challenges are also emerging (e.g., climate change, resource conflicts) that may undermine previously successful efforts to address historical threats 81 . To adapt to this rapidly changing landscape for recovery, conservation strategies must merge forwardlooking legislation to protect species with responsive resource management 82,83 . There is no silver bullet to reverse species declines, but successful efforts to recover populations must look beyond narrowly addressing conservation threats toward enabling the conditions for recovery in the context of sustainable human-nature systems.

Methods
Large carnivore species list. To build a comprehensive species list, we combined species trait databases developed for amniotes (Myrvold et al. 2015; n = 21,323) and vertebrates (Ripple et al. 2017; n = 27,647) and refined the list based on taxon-and ecosystem-specific criteria to retain a list of large carnivores. Specifically, we pooled candidate species from all vertebrate classes, pruning the list by (1) eliminating exclusively herbivorous families, (2) employing taxon-specific body mass thresholds drawn from previous literature, and (3) retaining only species whose primary dietary mode is carnivory. We restricted our list to species above the following taxon-specific body mass thresholds, following or approximating previously published large-carnivore size cutoffs where possible: Sharks and rays, marine teleost, marine mammal: 50 kg ( To narrow the resulting large vertebrate list further, we queried FishBase using the package rFishBase (v17.07) in the R statistical environment (version 1.2.1268) and restricted sharks, rays, and bony fishes to those with a mean trophic position ('DietTroph') of 4.0 or greater. For species not available in rFishBase (n = 155) we compiled an equivalent metric of trophic position from a database published by Sánchez-Hernández and Amundsen 84 . We acknowledge the limitations inherent in estimates of trophic position, including uneven sampling among species, seasonal variability, and ontogenetic diet shifts 84 and recognize that improved diet data could refine future species lists. To remove mammalian herbivores and omnivores with plant-centric diets, we retained only species identified by 85 as carnivores and, using the Phylacine 1.2 database 86 , we removed species with less than 50% carnivory listed.
We queried the IUCN Red List database (v2019. 3) and compiled current information on species-level extinction risk (status: Not Evaluated, Data Deficient, Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, Extinct), population trend (trend: increasing, decreasing, stable), ecosystem type, and geographic range. Except where noted, we analyzed only species with known status (i.e., not Data Deficient). We calculated the average age of most recent assessment for our species list and compared age of assessment metrics across vertebrate groups with a Kruskal-Wallis one-way analysis of variance, using the function kruskal.test() from the R package stats. We found a significant difference in age-of-assessment across groups (chi-squared = 159.4, df = 5, p < 0.001). We then used the function dunnTest from the R package FSA to perform post-hoc tests while accounting for multiple comparisons and found significant differences among all groups, with the exceptions of comparisons between reptiles/amphibians and bony fish, as well as between marine and terrestrial mammals (Fig. S3).

Species richness and range maps.
We estimated large carnivore species richness using IUCN Red List and BirdLife species range maps (BirdLife International and Handbook of the Birds of the World 2016; IUCN 2018). For each species' range map, we removed all polygons except those with "Origin" coded as either Native or Reintroduced and "Presence" coded as either Extant or Probably Extant. We then rasterized each species range at 5 km resolution. For species with altitude limits published in the IUCN Red List, we masked out areas outside these limits using the U.S. Geological Survey's Global 30 Arc-Second Elevation map (re-projected to 5 km). We summed up the individual species' raster range maps to form total large carnivore species richness. For mapping, we used separate scales to distinguish among terrestrial marine species richness, but combined freshwater and terrestrial species for visualization purposes. Because species may either lack spatial data or be classified as, for example, Possibly Extinct throughout their ranges, some of the species were not included in the richness map. In total, 9.4% (34/362) of the large carnivore species were excluded (Fig. S1).
We overlaid species range maps onto maps of marine biogeographic realms 87 and terrestrial realms (for both terrestrial and freshwater species) 88 . For each species, we calculated the area of its range within each realm. We also calculated the proportion of its range within each region realm within Marine and Terrestrial realm types. We masked out marine realms in the small coastal areas where the terrestrial and marine realm maps overlapped. We reported marine realms for species that are at least partly marine (according to IUCN Red List fact sheet pages) and terrestrial realms for species that are at least partly terrestrial or freshwater. Note: given known limitations of marine species range identification, terrestrial range maps likely offer greater accuracy with respect to small-scale species richness patterns. www.nature.com/scientificreports/ Taxonomic and geographic patterns of extinction risk and recovery. We tested whether each taxon (Table S2) or geographic region (Table S3) showed a disproportionate prevalence of recoveries (or ongoing declines) using chi-square goodness-of-fit tests. We tested whether the proportions of each population trend category/level (increasing, decreasing, stable) for each (1) taxon and (2) region/realm differed from expected as well as whether the proportions of each change in status category/level (improved, declined, unchanged) for each (3) taxon and (4) region/realm differed from expected. We informed the null expected distribution of outcomes using IUCN Red List data from 2007 to 2018. To inform the expected distributions of population trends across taxa (analysis 1), we calculated the proportion of each population trend category (increasing, decreasing, stable) across all assessed species belonging to each taxon. To inform the expected distributions of change-in-status across taxa (analysis 3), we compiled all genuine changes (see above) and calculated the proportion of each change-in-status level (improved, declined, unchanged) across all assessed species belonging to each taxon.
Finally, the proportions of population trend and change-in-status levels for all assessed species were tallied across all realms and used to inform the null expected distribution for the regional analyses (analyses 2 and 4 above, respectively). Most of these distributions were leptokurtic, with many species remaining unchanged. When the expected values were < 5, we obtained simulated p-values using Monte Carlo simulation. Significant chi-square goodness-of-fit tests were followed by post-hoc binomial tests with sequential Bonferroni corrections to obtain p-values for each specific outcome (e.g., Does the proportion of birds with decreasing population trend differ from expected?). We also conducted chi-square tests of independence for comparisons 1-4 above (e.g., Are taxon and population trend independent?). When expected values were < 5, p-values were obtained using Fisher's Exact Test.
Associations with recovery and ongoing declines. To examine recovery outcomes and their association with threats and conservation actions, we used multiple recovery metrics including population trend from the most recent assessment and change in status over time. For the latter, we obtained a complete history of IUCN Red List assessments and calculated the magnitude and direction of most recent change status (e.g., Vulnerable to Least Concern: + 2) and the cumulative change in status. Following 89 we limited changes in status to those that have occurred since each taxonomic group was comprehensively assessed (Mammals, 1996;Birds, 1988;Reptiles, 1980) or 1996 for all other taxa. To evaluate only genuine changes in extinction risk as a result of improvement or declines in conservation outlook (as opposed to status changes that resulted in updated population information) we referenced Table S6 of genuine changes in 35 (for changes prior to 2007) and annual lists of genuine and non-genuine changes provided by IUCN in Summary Statistics, Table 7 (2007-2019). Where species underwent multiple status changes, we calculated status change metrics using only genuine changes, making our results qualitatively similar to calculation of the Red List Index (RLI) for taxa that have undergone comprehensive assessment. We note that these recovery metrics are conservative indicators; change in extinction risk status, in particular, represents a high bar for recovery as 'no change' may indicate an absence of data or outdated assessment.
To evaluate drivers of recovery, we compiled information on conservation actions from the most recent IUCN assessments and compared patterns of actions employed for species with positive versus negative recovery outcomes. To do so, we compiled data for each species using the 11 IUCN-defined categories under 'Conservation Actions In-Place' (e.g., International Legislation) (Table S5). We then tested whether conservation actions were significantly associated with positive recovery outcomes using binomial logistic regression, where responses were positive only when status had 'improved' (merging 'unchanged' with 'declined' for this analysis) or when trend was 'increasing' (merging 'stable' with 'decreasing'). We employed backwards stepwise selection to identify the best performing binomial logistic regression model with respect to AIC and used the coefficients of the resulting model to infer the change in log-odds of recovery associated with each action. Because recoveries were dominated by marine mammals, we repeated the analysis with and without this taxonomic group in order to identify associations between recoveries and conservation actions that were attributable to this group alone.
To complement IUCN-defined conservation actions, we created a list of 15 common conservation actions (nested in 5 broader categories; see Table S5) based on the text of the IUCN assessment "Conservation Actions In Detail." We then tested whether conservation actions were significantly associated with positive recovery outcomes using binomial logistic regression, with statistical procedures identical to those described above for IUCN-defined categories.
We tested associations between IUCN listed threats and ongoing declines using binomial logistic regression. The Red List has well-known issues with its categorization of 'threats' and 'stresses' which conflate the sources of and responses to species declines, and which result in non-intuitive groupings (e.g., timber and hunting receiving the same 'threat' coding). We therefore re-categorized IUCN information into 23 author-generated categories of anthropogenic threat representing the relevant sector or human activity threatening the focal species (Tables S5,  S6), for example Energy, Hunting, Species Introductions (Note: Species Introductions refer to non-native species of any trophic level that may negatively impact the large carnivores via predation, competition, habitat degradation, etc.). Prior to converting threats and following IUCN Red List recommendations, we calculated the 'impact score' of each threat-by-species combination, using the 'severity' , 'scope' , and 'timing' values listed, and removed threats with low impact score. We further removed threats whose timing was listed as 'future' as these threats are unlikely to have altered previously recovery outcomes. To test the sensitivity of these restrictions, we compared significant associations with and without low-impact and future threats. The qualitative results were identical with only Conflict, Ecosystem Modification, and Hydrological changes significantly associated with multiple metrics of decline. We then employed binary logistic regression, where negative outcomes were restricted to elevated extinction risk (i.e., threatened status), decreasing trend, and declined status. The estimated change in the odds of